In recent years, silver halide color photographic light-sensitive materials have been significantly improved in image quality. The light-sensitive materials now on the market are excellent in graininess and sharpness, and it seems that photoprints (of service size) and slide films obtained from these materials almost satisfy users' requirements.
As for color reproducibility, however, there is yet room for improvement. Though light-sensitive materials have come to be able to provide a dye image of a higher purity (they can provide an image of a color which is vivid, sometimes far more vivid than the color of a subject), they cannot reproduce accurately some hues that have been regarded as difficult to be reproduced in a photograph. When photographing is performed with conventional light-sensitive materials, a color of the purple family that reflects light of not less than 600 nm in wavelength (a color having anomalous reflectance) such as purple and bluish purple, and a color of the green family such as green and yellowish green are likely to be reproduced as colors entirely different from original ones.
Meanwhile, color reproduction is greatly affected by spectral sensitivity distribution and the interimage effect (hereinafter referred to as IIE). Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) No. 2537/1975 and other publications disclose the use of a DIR compound for the manifestation of an IIE. A DIR compound is a compound that releases a development inhibitor or its precursor upon a coupling reaction with an oxidized color developing agent. A development inhibitor or its precursor released from a DIR compound hinders the development of other color-forming layers.
In the case of color negative films, a dye image can be prevented from becoming impure by the use of a colored coupler in an amount large enough to cancel an unnecessary absorption (a secondary absorption). An effect similar to IIE can be produced by the use of a sufficient amount of a colored coupler.
However, a large amount of a colored coupler inevitably increases the minimum density of a film, leading to difficulty in color or density correction at the time of printing, which eventually prolongs printing time or deteriorates the quality of the resulting photoprint.
The use of a colored coupler is effective only in improving color purity. A diffusible DIR, a compound capable of releasing a development inhibitor (or its precursor) that has a higher diffusibility, has come to be employed widely for its contribution to color purity improvement. This compound, however, has a defect such that it causes the hue of a subject to be reproduced differently if the direction in which a development inhibitor is diffused is not adequately controlled.
Japanese Patent Examined Publication No. 6207/1974 discloses bringing the spectral sensitivity distribution of each of blue- and red-sensitive silver halide emulsion layers (hereinafter abbreviated as blue- and red-sensitive layers) close to that of a green-sensitive silver halide emulsion layer (hereinafter abbreviated as a green-sensitive layer) by using a filter layer or the like in order to minimize variation in color reproduction caused by change in light source conditions.
This method is effective to some extent in preventing the color reproducibility of a light-sensitive material for photographing from varying due to a change in color temperature. However, by this method, it is impossible to improve the reproducibility for colors which are regarded as difficult to be reproduced.
In addition, by this method, sensitivity is considerably lowered, and, since the spectral sensitivity distribution curves of color-sensitive layers are caused to overlap with one another, the range of color reproduction narrows, and as a result, a color having a higher saturation cannot be reproduced accurately.
For accurate reproduction of a hue, shifting the spectral sensitivity distribution of a red-sensitive layer to the shorter wavelength region is important, since it has an effect of bringing the peak wavelength of the spectral sensitivity distribution of a light-sensitive material closer to that of the spectral sensitivity distribution of a human eye. This is especially important for the exact reproduction of a color that has anomalous reflectance, i.e., bluish purple (e.g. photographic reproduction of a bluish purple flower).
However, as mentioned above, when the spectral sensitivity distribution of a red-sensitive layer is shifted to the shorter wavelength region, a light-sensitive material cannot provide a dye image with a higher saturation; in particular, it cannot perform exact reproduction of skin color. When photographing is performed with such a light-sensitive material, skin color is reproduced to a color which is lacking healthy redness that is peculiar to the skin of a human being.
Japanese Patent O.P.I. Publication Nos. 20926/1978 and 131937/1984 each disclose a technique of bringing the spectral sensitivity distribution of a red-sensitive layer closer to that of a green-sensitive layer. However, this technique is not effective in improving color reproducibility, and involves the above-mentioned problems. Aiming at improving reproducibility for bluish green, Japanese Patent O.P.I. Publication No. 181144/1990 specifies a difference in sensitivity at 480 nm between a blue-sensitive layer and a green-sensitive layer and the density of a yellow filter layer.
Japanese Patent O.P.I. Publication No. 160449/1987 specifies IIE manifestation direction for each color-sensitive layer.
Japanese Patent O.P.I. Publication No. 160448/1987 discloses a method in which a cyan layer is provided to allow an IIE to be manifested in a red-sensitive layer, whereby the red-sensitive layer has a spectral sensitivity distribution close to that of a human eye. This method is accompanied by a problem such that the production cost is high due to an increased coating weight of silver and more complicated production procedures which are ascribable to the provision of an IIE manifesting layer. In addition, effects obtained by this method are not significant.
Meanwhile, to reproduce skin color more accurately, it is important to make the spectral sensitivity distribution curve of a G layer short-tailed in the longer wavelength region. If the spectral sensitivity distribution curve of a G layer is short-tailed in the longer wavelength region, the layer receives less light in photographing a red subject, causing the resulting photoprint to have a strong tinge of magenta. However, when the spectral sensitivity distribution curve of a G layer is short-tailed in the longer wavelength region, accurate reproduction of yellow cannot be performed. In such case, yellow in a photoprint has a tinge of magenta. Vivid yellow, such as the color of a lemon, cannot be reproduced exactly by this method.
As is understood from the foregoing, any of the conventional methods was unsatisfactory in color reproducibility. Under such circumstances, there has been a strong demand for a light-sensitive material with improved color reproducibility.